U.S. patent number 11,008,477 [Application Number 16/074,028] was granted by the patent office on 2021-05-18 for intaglio magnetic machine readable oxidative drying inks.
This patent grant is currently assigned to SICPA HOLDING SA. The grantee listed for this patent is SICPA HOLDING SA. Invention is credited to Jessica Krueger, Patrick Magnin, Cecile Pasquier.
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United States Patent |
11,008,477 |
Krueger , et al. |
May 18, 2021 |
Intaglio magnetic machine readable oxidative drying inks
Abstract
The present invention relates to the field of magnetic machine
readable oxidative drying suitable for intaglio printing of
security documents. In particular, the invention relates to
magnetic oxidative drying ink for intaglio printing on a substrate,
said magnetic oxidative drying ink having a viscosity in the range
of about 3 to about 60 Pa s at 40.degree. C. and 1000 s.sup.-1 and
comprising a) at least one oxidative drying varnish, b) a plurality
of core-shell pigment particles comprising a magnetic core and an
external layer made of silver and c) one or more stabilizers
selected from benzotriazole compounds.
Inventors: |
Krueger; Jessica (Les Paccots,
CH), Pasquier; Cecile (Marly, CH), Magnin;
Patrick (Evian-les-Bains, FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
SICPA HOLDING SA |
Prilly |
N/A |
CH |
|
|
Assignee: |
SICPA HOLDING SA (Prilly,
CH)
|
Family
ID: |
55450963 |
Appl.
No.: |
16/074,028 |
Filed: |
January 26, 2017 |
PCT
Filed: |
January 26, 2017 |
PCT No.: |
PCT/EP2017/051624 |
371(c)(1),(2),(4) Date: |
July 30, 2018 |
PCT
Pub. No.: |
WO2017/129666 |
PCT
Pub. Date: |
August 03, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190040271 A1 |
Feb 7, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Jan 29, 2016 [EP] |
|
|
16153347 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09D
11/037 (20130101); B41M 3/14 (20130101); C09D
11/03 (20130101); B41M 1/10 (20130101); C09D
11/10 (20130101); C08K 9/10 (20130101); C08K
5/3475 (20130101) |
Current International
Class: |
C09D
11/037 (20140101); B41M 1/10 (20060101); B41M
3/14 (20060101); C09D 11/03 (20140101); C09D
11/10 (20140101); C08K 5/3475 (20060101); C08K
9/10 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
0492208 |
|
Jul 1992 |
|
EP |
|
0340163 |
|
Dec 1992 |
|
EP |
|
0601483 |
|
Jun 1994 |
|
EP |
|
1046692 |
|
Oct 2000 |
|
EP |
|
1213338 |
|
Jun 2002 |
|
EP |
|
2014729 |
|
Jan 2009 |
|
EP |
|
S 62/190272 |
|
Aug 1987 |
|
JP |
|
S 63/218766 |
|
Sep 1988 |
|
JP |
|
H 02/80470 |
|
Mar 1990 |
|
JP |
|
2013-151644 |
|
Aug 2013 |
|
JP |
|
2007/022226 |
|
Feb 2007 |
|
WO |
|
WO 2008/083894 |
|
Jul 2008 |
|
WO |
|
WO 2010/115986 |
|
Oct 2010 |
|
WO |
|
WO 2014/086556 |
|
Jun 2014 |
|
WO |
|
WO 2014/124718 |
|
Aug 2014 |
|
WO |
|
Other References
English translation of EP 0492208, Jul. 1992; 6 pages. cited by
examiner .
English translation of JPS 62/190272, Aug. 1987; 8 pages. cited by
examiner .
English translation of JPS 63/218766, Sep. 1988; 6 pages. cited by
examiner .
English translation of JPH 02/80470, Mar. 1990; 5 pages. cited by
examiner .
International Search Report and Written Opinion issued with respect
to application No. PCT/EP2017/051624; dated Apr. 4, 2017. cited by
applicant .
Chem. Rev. 99 (1999), G. Pfaff and P. Reynders, pp. 1963-1981.
cited by applicant .
Japanese Office Action in counterpart Japanese Application No.
2018-535158 dated Sep. 29, 2020 (and English language translation
of the Office Action). cited by applicant.
|
Primary Examiner: Klemanski; Helene
Attorney, Agent or Firm: Muncy, Geissler, Olds & Lowe,
P.C.
Claims
The invention claimed is:
1. A magnetic oxidative drying ink for intaglio printing on a
substrate, said magnetic oxidative drying ink having a viscosity in
the range of about 3 to about 60 Pa s at 40.degree. C. and 1000
s.sup.-1 and comprising a) at least one oxidative drying varnish,
b) a plurality of core-shell pigment particles comprising a
magnetic core and an external layer made of silver and c) one or
more stabilizers selected from benzotriazole compounds having the
formula (I) ##STR00012## wherein R.sub.1-R.sub.4 may be the same or
may be different and are independently selected from the group
consisting of hydrogen, linear C.sub.1-C.sub.4 alkyls, branched
C.sub.3-C.sub.4 alkyls, C.sub.1-C.sub.4 linear haloalkyls, and
branched C.sub.3-C.sub.4 haloalkyls.
2. The magnetic oxidative drying ink according to claim 1, wherein
R.sub.1-R.sub.4 are may be the same or may be different and are
independently selected from the group consisting of hydrogen,
linear C.sub.1-C.sub.2 alkyls, and C.sub.1-C.sub.2 linear
haloalkyls.
3. The magnetic oxidative drying ink according to claim 1, wherein
the core-shell pigment particles comprise a magnetic core
surrounded by a first layer made of one or more inorganic materials
and the external layer made of silver; or a magnetic core
surrounded by a first layer made of one or more organic materials
and the external layer made of silver.
4. The magnetic oxidative drying ink according to claim 1, wherein
the magnetic core is made of one or more materials selected from
the group consisting of iron, Fe.sub.2O.sub.3 and Fe.sub.3O.sub.4
and mixtures or combinations thereof, and/or the one or more
inorganic materials are selected from the group consisting of
metals selected from the group consisting of silver, aluminum,
nickel, palladium, platinum, copper, gold, rhodium, zinc, iridium
and their alloys; metal oxides and metal sulfides and/or the one or
more organic materials are selected from the group consisting of
polyacrylates, polystyrenes, parylenes, alkoxysilanes and mixtures
thereof.
5. The magnetic oxidative drying ink according to claim 1, wherein
the core-shell pigment particles are present in an amount from
about 3 to about 70 wt-%, the weight percents being based on the
total weight of the magnetic oxidative drying ink.
6. The magnetic oxidative drying ink according to claim 1, wherein
the one or more benzotriazole compounds are present in an amount
from about 0.1 to about 20 wt-%, the weight percents being based on
the total weight of the magnetic oxidative drying ink.
7. The magnetic oxidative drying ink according to claim 1, further
comprising one or more waxes.
8. The magnetic oxidative drying ink according to claim 7, wherein
the one or more waxes are present in an amount from about 0.1 to
about 15 wt-%, the weight percents being based on the total weight
of the magnetic oxidative drying ink.
9. The magnetic oxidative drying ink according to claim 1, further
comprising one or more driers.
10. The magnetic oxidative drying ink according to claim 9, wherein
the one or more driers are present in an amount from about 0.01 to
about 10 wt-%, the weight percents being based on the total weight
of the magnetic oxidative drying ink.
11. A process for producing the magnetic oxidative drying ink
recited in claim 1, comprising a step of dispersing, mixing and/or
milling the at least one oxidative drying varnish with the
plurality of core-shell pigment particles comprising a magnetic
core and an external layer made of silver and the one or more
stabilizers selected from benzotriazole compounds having the
formula (I).
12. A security feature comprising a layer or coating made of the
magnetic oxidative drying ink recited in claim 1.
13. A security document comprising a substrate and one or more
security features recited in claim 12.
14. A process for producing a security document, comprising a step
a) of applying by an intaglio printing process the magnetic
oxidative drying ink recited in claim 1 onto a substrate.
15. The process according to claim 14, further comprising a step b)
of drying the magnetic oxidative drying ink in the presence of air
so as to form a layer or coating on the substrate, said step of
drying being performed after the step a).
Description
The present invention relates to the field of the protection of
security document against counterfeit and illegal reproduction. In
particular, the present invention relates to the field of magnetic
machine readable oxidative drying inks suitable for intaglio
printing of security documents.
BACKGROUND OF THE INVENTION
Magnetic inks have been widely used in the field of security
documents, in particular for banknotes printing, to confer the
security document an additional covert security feature. The
protection of security document against counterfeit and illegal
reproduction provided by covert security features relies on the
concept that such features typically require specialized equipment
and knowledge for their detection. Due to their magnetic
properties, security features printed with a magnetic ink may be
machine authenticated, given that magnetism can be easily sensed by
electronic means. Examples of the use of magnetic features for
banknotes are disclosed in U.S. Pat. No. 3,599,153 and in U.S. Pat.
No. 3,618,765. However, commonly used magnetic materials in
security inks have a dark optical appearance and may be only used
for the production of dark or black security features. Therefore,
commonly used magnetic materials in security inks do not allow for
the possibility to create pure colors, particularly bright hues as
a result of the inherent dark color of the magnetic materials thus
limiting the gamut of colors for the design of security
documents.
Magnetic security features may be prepared through an intaglio
printing process (also referred in the art as engraved copper plate
printing and engraved steel die printing), which is capable of
depositing a sufficiently high amount of magnetic material on the
substrate so as to allow for its detection and sensing.
Intaglio printing processes refer to printing methods used in
particular in the field of security documents. The intaglio
printing process is known to be the most consistent and high
quality printing process for producing fine tapering lines and is
therefore the printing technology of choice for fine design in the
field of security documents, in particular banknotes and stamps. In
particular, one of the distinguishing features of the intaglio
printing process is that the layer thickness of the ink transferred
to the substrate may be varied from a few micrometers to several
tens of micrometers by using correspondingly shallow or deep
engravings on the intaglio printing device. As mentioned hereabove,
the layer thickness of intaglio printed security features thus
allow a sufficiently high amount of material on the substrate for
its detection and sensing.
To overcome the dark optical appearance of commonly used magnetic
machine readable inks and security features made of said inks, WO
2010/115986 A2 discloses magnetic machine readable intaglio inks
comprising magnetic multilayer pigment particles so as to form
magnetic layers by intaglio processes, wherein said magnetic layer
can be detected and sensed by automatic machinery (machine
readability) and do not suffer from a dark appearance. However,
intaglio inks comprising magnetic pigment particles with external
layer made of silver may suffer from a limited stability.
Oxidative drying inks are commonly used for intaglio printing
processes, said inks refer to inks which dry by oxidation in the
presence of oxygen, in particular in the presence of the oxygen of
the atmosphere. During the drying process, the oxygen combines with
one or more components of the ink vehicle, converting the ink to a
semi-solid or a solid state. The process may be accelerated by the
use of driers also referred in the art as catalysts, siccative
agents, desiccatives or dessicators, such as metallic salts and/or
by the application of a thermal treatment.
Intaglio oxidative drying inks may suffer from a so-called "set-of"
problem which is the transfer of ink from one printed sheet to the
back side of the next following printed sheet in the stack, or to
the back of an endless sheet in a web. Although this is a problem
may be encountered with any industrial printing process such as
intaglio printing methods wherein the pronounced relief of the
printing method may accentuate the problem of set-off. With the
state of the art oxidatively drying intaglio inks, the set-off
issues have been reduced through the optimization of the ink
formulation; however, deep engraving features may still result in
undesirable set-off.
There remains a need for magnetic machine readable oxidative drying
inks for intaglio printing processes that combine a good stability
upon storage so as to improve the shelf life of said inks, a good
stability of intaglio printed security features as well as good
drying performance so as to avoid set-off problems.
SUMMARY
Accordingly, it is an object of the present invention to overcome
the deficiencies of the prior art discussed above. This is achieved
by the provision of taking advantage of one or more benzotriazole
compounds having the formula (I) in a magnetic oxidative drying ink
for intaglio printing on a substrate, wherein said magnetic
oxidative drying ink has a viscosity in the range of about 3 to
about 60 Pa s at 40.degree. C. and 1000 s.sup.-1 and comprises a)
at least one oxidative drying varnish, b) a plurality of core-shell
pigment particles comprising a magnetic core and an external layer
made of silver.
Described herein are magnetic oxidative drying inks for intaglio
printing on a substrate said magnetic oxidative drying ink having a
viscosity in the range of about 3 to about 60 Pa s at 40.degree. C.
and 1000 s.sup.-1 and comprising a) at least one oxidative drying
varnish, b) a plurality of core-shell pigment particles comprising
a magnetic core and an external layer made of silver and c) one or
more stabilizers selected from benzotriazole compounds having the
formula (I)
##STR00001## wherein R.sub.1-R.sub.4 may be the same or may be
different and are independently selected from the group consisting
of hydrogen, linear C.sub.1-C.sub.4 alkyls, branched
C.sub.3-C.sub.4 alkyls, C.sub.1-C.sub.4 linear haloalkyls, and
branched C.sub.3-C.sub.4 haloalkyls.
Described herein are processes for producing the magnetic oxidative
drying inks described herein, said processes comprising a step of
dispersing, mixing and/or milling the at least one oxidative drying
varnish described herein with the plurality of core-shell pigment
particles described herein and the one or more stabilizers selected
from benzotriazole compounds having the formula (I) described
herein.
Described herein are uses of the one or more benzotriazole
compounds described herein as stabilizers in a magnetic oxidative
drying ink for intaglio printing on a substrate described
herein.
Described herein are security features comprising a layer or
coating made of the magnetic oxidative drying ink described
herein.
Described herein are processes for producing the security features
described herein and security features obtained thereof, said
processes comprising a step of applying by an intaglio printing
process the magnetic oxidative drying ink described herein on a
substrate such as those described herein.
Described herein are uses of the security features described herein
for the protection of a security document against counterfeiting or
fraud and security documents comprising one or more of the security
features described herein.
Described herein are security documents comprising one or more
security features described herein.
Described herein are processes for producing the security documents
described herein and security documents obtained thereof, said
processes comprising a step a) of applying by an intaglio printing
process the magnetic oxidative drying ink described herein onto a
substrate such as those described herein.
DETAILED DESCRIPTION
The following definitions are to be used to interpret the meaning
of the terms discussed in the description and recited in the
claims.
As used herein, the article "a" indicates one as well as more than
one and does not necessarily limit its referent noun to the
singular.
As used herein, the terms "about" means that the amount or value in
question may be the value designated or some other value about the
same. The phrases are intended to convey that similar values within
a range of .+-.5% of the indicated value promote equivalent results
or effects according to the invention.
As used herein, the term "and/or" or "or/and" means that either all
or only one of the elements of said group may be present. For
example, "A and/or B" shall mean "only A, or only B, or both A and
B".
As used herein, the term "at least" is meant to define one or more
than one, for example one or two or three.
The term "security feature" is used to denote an image, pattern or
graphic element that can be used for authentication purposes.
The term "security document" refers to a document which is usually
protected against counterfeit or fraud by at least one security
feature. Examples of security documents include without limitation
value documents and value commercial goods.
The present invention provides magnetic oxidative drying inks
suitable for intaglio printing processes, in particular for
intaglio printing processes for producing security features on
security documents. The magnetic oxidative drying inks for intaglio
printing processes described herein have a viscosity in the range
of about 3 to about 60 Pa s at 40.degree. C. and 1000 s.sup.-1, the
viscosities being measured on a Haake Roto-Visco RV1 with a cone
plate 1. The magnetic oxidative drying inks described herein
comprises at least one oxidative drying varnish such as those
described herein, a plurality of core-shell pigment particles
comprising a magnetic core and an external layer made of silver
such as those described herein, one or more benzotriazole compounds
such as those described herein, and optionally one or more
compounds, additives and/or ingredients such as those described
herein.
The magnetic oxidative drying inks described herein comprise a
plurality of core-shell pigment particles comprising a magnetic
core and an external layer made of silver. By "external layer", it
is meant that said layer faces the environment, i.e. faces the
magnetic oxidative drying ink wherein the core-shell pigment
particles are dispersed.
The magnetic oxidative drying inks described herein preferably
comprise the core-shell pigment particles described herein in an
amount from about 3 to about 70 and more preferably from about 5 to
about 50 wt-% and still more preferably from about 10 to about 30
wt-%, the weight percents being based on the total weight of the
magnetic oxidative drying ink.
The size of the core-shell pigment particles described herein is
preferably between about 0.1 and about 30 microns, preferably
between about 0.5 and about 15 microns.
The magnetic cores described herein are made of one or more
soft-magnetic, semi-hard (12.5-125 Oe) or hard-magnetic type
(ideally, but not limited to, 2 to 5000 Oe) materials. The magnetic
cores described herein preferably comprise one or more magnetic
materials selected from the group consisting of magnetic metals (in
particular iron, cobalt and nickel); magnetic metal oxides (in
particular FeO.sub.23, Fe.sub.3O.sub.4, CrO.sub.2, hexaferrites
such as for example barium hexaferrites and strontium hexaferrites,
perovskites and A.sub.3B.sub.5O.sub.12 garnets, wherein A is a
trivalent rare earth ion and B is A.sup.3+, Cr.sup.3+, Fe.sup.3+,
Ga.sup.3+ or Bi.sup.3+); magnetic metal alloys (in particular iron
alloys, iron-nickel alloys, iron-cobalt alloys, nickel-cobalt
alloys, iron-nickel alloy nitrides and iron-nickel-cobalt alloy
nitrides) and mixtures or combinations thereof. More preferably,
the magnetic cores described herein comprise one or more magnetic
materials selected from the group consisting of iron,
Fe.sub.2O.sub.3 and Fe.sub.3O.sub.4 and mixtures or combinations
thereof.
According to one embodiment, the core-shell pigment particles
described herein preferably comprises a magnetic core such as those
described herein, a first layer (intermediate layer) made of one or
more inorganic materials and a second layer (external layer facing
the environment) made of silver, wherein the one or more inorganic
materials are preferably selected from the group consisting of
metals selected from the group consisting of silver, aluminum,
nickel, palladium, platinum, palladium, copper, gold, rhodium,
zinc, iridium and their alloys; metal oxides (preferably selected
from the group consisting of MgO and ZnO, Al.sub.2O.sub.3,
Y.sub.2O.sub.3. Ln.sub.2O.sub.3 (wherein Ln is a lanthanide),
SiO.sub.2, TiO.sub.2, ZrO.sub.2, CeO.sub.2 and mixtures thereof)
and metal sulfides (preferably selected from the group consisting
of ZnS; CaS and mixtures thereof). Preferably, the core-shell
pigment particles described herein preferably comprises a magnetic
core, a first layer (intermediate layer) made of one or more
inorganic materials and an external layer made of silver, wherein
the one or more inorganic materials are metal oxides such as those
described hereabove and preferably selected from the group
consisting of SiO.sub.2, TiO.sub.2 and Y.sub.2O.sub.3.
According to another embodiment, the core-shell pigment particles
described herein preferably comprises a magnetic core, a first
layer (intermediate layer) made of one or more organic materials
and a second layer (external layer facing the environment) made of
silver, wherein the one or more organic materials are preferably
selected from the group consisting of polyacrylates (preferably
poly(methyl methacrylate, PMMA), polystyrenes, parylenes,
alkoxysilanes (preferably 3-methacryloxypropyl trimethoxysilane,
TMP), and combinations thereof, more preferably the one or more
organic materials are selected from the group consisting of
poly(methyl methacrylate) and 3-methacryloxypropyl
trimethoxysilane.
All suitable deposition processes (physical and/or chemical) can be
used to deposit silver layers, organic layers and inorganic layers
onto the magnetic core described herein. Typical examples of
deposition processes or coating process include without limitation
chemical vapor deposition (CVD) and wet-chemical coating. In the
case of forming an organic material layer, these core-shell pigment
particles may be prepared by a method consisting of dispersing the
magnetic cores described herein in a liquid phase and an organic
layer is formed on the particles by emulsion polymerization
(liquid-phase polymerization method), or by a method in which the
organic layer is formed in a vapor phase (CVD or PVD), or of still
others methods known by the skilled one in the art.
In a particularly preferred embodiment, the magnetic oxidative
drying ink described herein comprises the core-shell pigment
particles described herein, wherein said particles have a bulk
lightness L* higher than 60 according to the CIELAB (1976) scale,
preferably higher than 75, most preferably higher than 80.
In a preferred embodiment of the present invention the ink has a
diffuse infrared (IR) reflectance between 800 and 1000 nm, which is
higher than 50%, preferably higher than 60%.
The oxidative drying inks described herein comprise one or more one
or more stabilizers selected from benzotriazole compounds having
the formula (I):
##STR00002## wherein R.sub.1-R.sub.4 may be the same or may be
different and are independently selected from the group consisting
of hydrogen, linear C.sub.1-C.sub.4 alkyls, branched
C.sub.3-C.sub.4 alkyls, C.sub.1-C.sub.4 linear haloalkyls, wherein
the halo atom is preferably independently selected from the group
consisting of fluorine, chlorine and bromine, more preferably
fluorine and branched C.sub.3-C.sub.4 haloalkyls, wherein the halo
atom is preferably independently selected from the group consisting
of fluorine, chlorine and bromine, more preferably fluorine.
As used herein, the term "linear C.sub.1-C.sub.4 alkyls" refers to
linear alkyl groups having from one to four carbon atoms, i.e.
methyl, ethyl, propyl and butyl groups.
As used herein, the term "branched C.sub.3-C.sub.4 alkyls" refers
to branched alkyl groups having three or four carbon atoms, i.e.
isopropyl, isobutyl, sec-butyl and tert-butyl groups.
As used herein, the term "C.sub.1-C.sub.4 linear haloalkyls" refers
to linear alkyl groups having from one to four carbon atoms,
wherein one or more hydrogen atoms have been replaced by a halo
atom.
As used herein, the term "branched C.sub.3-C.sub.4 haloalkyls"
refers to branched alkyl groups having three or four carbon atoms,
wherein one or more hydrogen atoms have been replaced by a halo
atom.
It should further be appreciated that the invention also extends to
compounds in which one or more of the atoms have been replaced by
an isotopic variant, such as for example one or more hydrogen atoms
may be replaced by .sup.2H or .sup.3H and/or one or more carbon
atoms may be replaced by .sup.14C or .sup.13C.
Preferably, the oxidative drying inks described herein comprise one
or more one or more stabilizers selected from benzotriazole
compounds having the formula (I):
##STR00003## wherein R.sub.1-R.sub.4 may be the same or may be
different and are independently selected from the group consisting
of hydrogen, linear C.sub.1-C.sub.2 alkyls, and C.sub.1-C.sub.2
linear haloalkyls, wherein the halo atom is preferably
independently selected from the group consisting of fluorine,
chlorine and bromine, more preferably fluorine.
More preferably, the oxidative drying inks described herein
comprise one or more one or more stabilizers selected from
benzotriazole compounds having the formula (I):
##STR00004## wherein R.sub.1-R.sub.4 may be the same or may be
different and are independently selected from the group consisting
of hydrogen, C.sub.1 alkyls (i.e. methyl groups), and C.sub.1
haloalkyls (i.e. halomethyl groups), wherein the halo atom is
preferably independently selected from the group consisting of
fluorine, chlorine and bromine, more preferably fluorine.
According to one embodiment, the one or more benzotriazole
compounds described herein comprise R.sub.1-R.sub.4, wherein
R.sub.1-R.sub.4 are hydrogens.
According to another embodiment, the one or more benzotriazole
compounds described herein comprise R.sub.1-R.sub.4, wherein three
radicals of R.sub.1-R.sub.4 are hydrogens and one radical is a
methyl or ethyl group, preferably a methyl group.
According to another embodiment, the one or more benzotriazole
compounds described herein comprise R.sub.1-R.sub.4, wherein three
radicals of R.sub.1-R.sub.4 are hydrogens and one radical is a
halomethyl group, preferably a trihalomethyl group and more
preferably a trifluoromethyl group.
Also described herein are uses of the one or more benzotriazole
compounds having the formula (I) described herein as stabilizers
for the magnetic oxidative drying inks described herein for
printing by an intaglio process on a substrate.
The magnetic oxidative drying inks described preferably comprises
the one or more benzotriazole compounds described herein in an
amount from about 0.1 to about 20 wt-%, preferably from about 0.5
to about 10 and still more preferably from about 1 to about 5 wt-%,
the weight percents being based on the total weight of the
oxidative drying ink.
The magnetic oxidative drying inks described herein comprise at
least one oxidative drying varnish. The term "varnish" is also
referred in the art as resin, binder or ink vehicle. The at least
one oxidative drying varnish is preferably present in the
oxidatively drying inks described herein in an amount from about 10
to about 90 wt-%, the weight percents being based on the total
weight of the magnetic oxidative drying ink.
The oxidative drying varnishes for the oxidatively drying inks
described herein are drying varnishes, i.e. vanishes that cure
under the action of oxygen, for instance oxygen from the air
("air-drying"). Alternatively, and with the aim of accelerating the
drying process, the drying process may be performed under hot air,
an infrared source or any combination of hot air and an infrared
source.
Oxidative drying varnishes are typically polymers comprising
unsaturated fatty acid residues, saturated fatty acids residues or
mixtures thereof, as generally known in the art. Preferably the
oxidative drying varnishes described herein comprise unsaturated
fatty acid residues to ensure the air drying properties.
Particularly preferred oxidative drying varnishes are resins
comprising unsaturated acid groups, even more preferred are resins
comprising unsaturated carboxylic acid groups. However the resins
may also comprise saturated fatty acids residues. Preferably the
oxidative drying varnishes described herein comprise acid groups,
i.e. the oxidative drying varnishes are selected among acid
modified resins. The oxidative drying varnishes described herein
may be selected from the group consisting of alkyd resins, vinyl
polymers, polyurethane resins, hyperbranched resins, rosin-modified
maleic resins, rosin-modified phenol resins, rosin ester, petroleum
resin-modified rosin ester, petroleum resin-modified alkyd resin,
alkyd resin-modified rosin/phenol resin, alkyd resin-modified rosin
ester, acrylic-modified rosin/phenol resin, acrylic-modified rosin
ester, urethane-modified rosin/phenol resin, urethane-modified
rosin ester, urethane-modified alkyd resin, epoxy-modified
rosin/phenol resin, epoxy-modified alkyd resin, terpene resins
nitrocellulose resins, polyolefins, polyamides, acrylic resins and
combinations or mixtures thereof. Polymers and resins are herein
interchangeably used.
Saturated and unsaturated fatty acid compounds may be obtained from
natural and/or artificial sources. Natural sources include animal
sources and/or plant sources. Animal sources may comprise animal
fat, butter fat, fish oil, lard, liver fats, tuna fish oil, sperm
whale oil and/or tallow oil and waxes. Plant sources may comprise
waxes and/or oils such as vegetable oils and/or non-vegetable oils.
Examples of plant oils include without limitation bitter gourd,
borage, calendula, canola, castor, china wood, coconut, conifer
seed, corn, cottonseed, dehydrated castor, flaxseed, grape seed,
Jacaranda mimosifolla seed, linseed oil, palm, palm kernel, peanut,
pomegranate seed, rapeseed, safflower, snake gourd, soya (bean),
sunflower, tall, tung and wheat germ. Artificial sources include
synthetic waxes (such as micro crystalline and/or paraffin wax),
distilling tail oil and/or chemical or biochemical synthesis
methods. Suitable fatty acids also include
(Z)-hexadan-9-enoic[palmitoleic]acid (C.sub.16H.sub.30O.sub.2),
(Z)-octadecan-9-enoic[oleic]acid (C.sub.18H.sub.34O.sub.2),
(9Z,11E,13E)-octadeca-9,11,13-trienoic[.alpha.-eleostearic]acid
(C.sub.18H.sub.30O.sub.2), licanic acid,
(9Z,12Z)-octadeca-9,12-dienoic[inoeic]acid
(C.sub.18H.sub.32O.sub.2),
(5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic[arachidonic]acid
(C.sub.20H.sub.32O.sub.2),
12-hydroxy-(9Z)-octadeca-9-enoic[ricinoleic]acid
(C.sub.18H.sub.34O.sub.3), (Z)-docosan-13-enoic[erucic]acid
(C.sub.22H.sub.42O.sub.3), (Z)-eicosan-9-enoic[gadoleic]acid
(C.sub.20H.sub.38O.sub.2),
(7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoic[clupanodonic]
acid and mixtures thereof.
Suitable fatty acids are ethylenically unsaturated conjugated or
non-conjugated C2-C24 carboxylic acids, such as myristoleic,
palmitoleic, arachidonic, erucic, gadoleic, clupanadonic, oleic,
ricinoleic, linoleic, linolenic, licanic, nisinic acid and
eleostearic acids or mixtures thereof. Those fatty acids are
typically used in the form of mixtures of fatty acids derived from
natural or synthetic oils.
The magnetic oxidative drying inks described herein preferably
comprise one or more driers (also referred in the art as catalysts,
siccatives, siccative agents, desiccatives or dessicators) to speed
up the oxidation process. Examples of driers include inorganic or
organic salts of metal(s), metallic soaps of organic acids, metal
complexes and metal complex salts. Suitable driers include without
limitation polyvalent salts containing cobalt, calcium, copper,
zinc, iron, zirconium, manganese, barium, zinc, strontium, lithium,
vanadium and potassium as the cation(s); and halides, nitrates,
sulphates, carboxylates like acetates, ethylhexanoates, octanoates
and naphtenates or acetoacetonates as the anion(s). When present,
the one or more driers used in the magnetic oxidative drying ink
described herein are preferably present in an amount from about
0.01 to about 10 wt-%, more preferably in an amount from about 0.1
to about 5 wt-%, the weight percents being based on the total
weight of the magnetic oxidative drying ink.
The magnetic oxidative drying inks described herein may further
comprise one or more surfactants, in particular hydrophilic
macromolecular surfactants such as those described e.g. in EP 0 340
163 BI. The role of the optional surfactants is to help wiping off
the excess of ink present on the printing cylinder just before
contacting said printing cylinder with the substrate. This process
of wiping off the excess of ink is part of any high-speed,
industrial intaglio printing process and is carried out using a
tissue or a paper roll ("calico"), or a polymer wiping cylinder and
a cleansing water-based solution ("wiping solution"). In this case,
the optional surfactants are used to emulsify the excess of ink in
the cleansing solution. Said surfactants may be nonionic, anionic
or cationic as well as zwitterionic ones. In the case of
hydrophilic macromolecular surfactants, the functional groups are
for example carboxylic or sulfonic acid groups, hydroxyl groups,
ether groups or primary, secondary, tertiary or quaternary amino
groups. The acid groups may be neutralized with amines,
alcanolamines or preferably inorganic bases, or combinations
thereof. Primary, secondary and tertiary amino groups may be
neutralized with inorganic or organic acids such as sulfonic acids,
formic acid, acetic acid, trifluoroacetic acid and others.
Particularly preferred are anionic macromolecular surfactants
(AMS), such as those described in EP 2 014 729 A1.
The magnetic oxidative drying inks described herein may be color
constant inks or optically variable inks.
According to one aspect of the present invention, the magnetic
oxidative drying inks described herein are color constant
composition inks preferably comprising a) one or more dyes, and/or
b) inorganic pigments, organic pigments or mixtures thereof. Dyes
suitable for inks are known in the art and are preferably selected
from the group comprising reactive dyes, direct dyes, anionic dyes,
cationic dyes, acid dyes, basic dyes, food dyes, metal-complex
dyes, solvent dyes and mixtures thereof. Typical examples of
suitable dyes include without limitation coumarines, cyanines,
oxazines, uranines, phtalocyanines, indolinocyanines,
triphenylmethanes, naphtalocyanines, indonanaphtalo-metal dyes,
anthraquinones, anthrapyridones, azo dyes, rhodamines, squarilium
dyes, croconium dyes. Typical examples of dyes suitable for the
present invention include without limitation C.I. Acid Yellow 1, 3,
5, 7, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 54, 59, 61,
70, 72, 73, 75, 76, 78, 79, 98, 99, 110, 111, 121, 127, 131, 135,
142, 157, 162, 164, 165, 194, 204, 236, 245; C.I. Direct Yellow 1,
8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98,
106, 107, 110, 132, 142, 144; C.I. Basic Yellow 13, 28, 65; C.I.
Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18,
22, 23, 24, 25, 26, 27, 37, 42; C.I. Food Yellow 3, 4; C.I. Acid
Orange 1, 3, 7, 10, 20, 76, 142, 144; C.I. Basic Orange 1, 2, 59;
C.I. Food Orange 2; C.I. Orange B; C.I. Acid Red 1, 4, 6, 8, 9, 13,
14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 73, 75, 77, 80, 82, 85,
87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129,
130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183,
184, 186, 194, 198, 209, 211, 215, 219, 221, 249, 252, 254, 262,
265, 274, 282, 289, 303, 317, 320, 321, 322, 357, 359; C.I. Basic
Red 1, 2, 14, 28; C.I. Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23,
24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89,
95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230,
231, 253; C.I. Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15,
16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37,
38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, 108, 180;
C.I. Food Red 1, 7, 9, 14; C.I. Acid Blue 1, 7, 9, 15, 20, 22, 23,
25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83,
90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129,
130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168,
170, 171, 182, 183, 184, 187, 192, 193, 199, 203, 204, 205, 229,
234, 236, 249, 254, 285; C.I. Basic Blue 1, 3, 5, 7, 8, 9, 11, 55,
81; C.I. Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80,
86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192,
193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236,
237, 246, 248, 249; C.I. Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13,
14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37,
38, 39, 40, 41, 43, 44, 46, 77; C.I. Food Blue 1, 2; C.I. Acid
Green 1, 3, 5, 16, 26, 104; C.I. Basic Green 1, 4; C.I: Food Green
3: C.I. Acid Violet 9, 17, 90, 102, 121: C.I. Basic Violet 2, 3,
10, 11, 21: C.I. Acid Brown 101, 103, 165, 266, 268, 355, 357, 365,
384; C.I. Basic Brown 1; C.I. Acid Black 1, 2, 7, 24, 26, 29, 31,
48, 50, 51, 52, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94, 107, 108,
109, 110, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155,
156, 157, 158, 159, 191, 194; C.I. Direct Black 17, 19, 22, 32, 39,
51, 56, 62, 71, 74, 77, 94, 105, 106, 107, 108, 112, 113, 117, 118,
132, 133, 146, 154, 168; C.I. Reactive Black 1, 3, 4, 5, 6, 8, 9,
10, 12, 13, 14, 18, 31; C.I. Food Black 2; C.I. Solvent Yellow 19,
C.I. Solvent Orange 45, C.I. Solvent Red 8, C.I. Solvent Green 7,
C.I. Solvent Blue 7, C.I. Solvent Black 7; C.I. Disperse Yellow 3,
C.I. Disperse Red 4, 60, C.I. Disperse Blue 3, and metal azo dyes
disclosed in U.S. Pat. Nos. 5,074,914, 5,997,622, 6,001,161, JP
02-080470, JP 62-190272, JP 63-218766. Suitable dyes for the
present invention may be infrared absorbing dyes or luminescent
dyes. When present, the one or more dyes used in the magnetic
oxidative drying ink described herein are preferably present in an
amount from about 1 to about 20 wt-%, the weight percents being
based on the total weight of the magnetic oxidative drying ink.
Typical examples of organic and inorganic pigments include without
limitation C.I. Pigment Yellow 12, C.I. Pigment Yellow 42, C.I.
Pigment Yellow 93, 109, C.I. Pigment Yellow 110, C.I. Pigment
Yellow 147, C.I. Pigment Yellow 173, C.I. Pigment Orange 34, C.I.
Pigment Orange 48, C.I. Pigment Orange 49, C.I. Pigment Orange 61,
C.I. Pigment Orange 71 C.I. Pigment Orange 73, C.I. Pigment Red 9,
C.I. Pigment Red 22, C.I. Pigment Red 23, C.I. Pigment Red 67, C.I.
Pigment Red 122, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I.
Pigment Red 170, C.I. Pigment Red 177, C.I. Pigment Red 179, C.I.
Pigment Red 185, C.I. Pigment Red 202, C.I. Pigment Red 224, C.I.
Pigment Brown 6, C.I. Pigment Brown 7, C.I. Pigment Red 242, C.I.
Pigment Red 254. C.I. Pigment Red 264, C.I. Pigment Brown 23, C.I.
Pigment Blue 15, C.I. Pigment Blue 15:3, C.I. Pigment Blue 60, C.I.
Pigment Violet 19, C.I. Pigment Violet 23, C.I. Pigment Violet 32,
C.I. Pigment Violet 37, C.I. Pigment Green 7, C.I. Pigment Green
36, C.I. Pigment Black 7, C.I. Pigment Black 11, C. I. Pigment
White 4, C.I. Pigment White 6, C.I. Pigment White 7, C.I. Pigment
White 21, C. I. Pigment White 22, antimony yellow, lead chromate,
lead chromate sulfate, lead molybdate, ultramarine blue, cobalt
blue, manganese blue, chrome oxide green, hydrated chrome oxide
green, cobalt green, cerium sulfide, cadmium sulfide, cadmium
sulfoselenides, zinc ferrite, bismuth vanadate, Prussian blue,
mixed metal oxides, azo, azomethine, methine, anthraquinone,
phthalocyanine, perinone, perylene, diketopyrrolopyrrole,
thioindigo, thiazinindigo, dioxazine, iminoisoindoline,
iminoisoindolinone, quinacridone, flavanthrone, indanthrone,
anthrapyrimidine and quinophthalone pigments. When present, the
inorganic pigments, organic pigments or mixtures thereof described
herein are preferably present in an amount from about 0.1 to about
45 wt-%, the weight percents being based on the total weight of the
oxidative drying ink.
According to one aspect of the present invention, the magnetic
oxidative drying inks described herein are optically variable inks
and comprise optically variable pigments or a mixture of different
optically variable pigments. Optically variable inks may further
comprise one or more color constant pigments. Optically variable
inks preferably comprise optically variable pigments or a mixture
of different optically variable pigments, wherein the optically
variable pigments are preferably selected from the group consisting
of thin film interference pigments, interference coated pigments,
cholesteric liquid crystal pigments and mixtures thereof. When
present the optically variable pigments are preferably comprised in
the magnetic oxidative drying ink described herein in an amount
between about 5 and about 40 wt-% and more preferably in an amount
between about 10 and about 35 wt-%, the weight percents being based
on the total weight of the magnetic oxidative drying ink.
Suitable thin film interference pigments exhibiting optically
variable characteristics are known to those skilled in the art and
disclosed in U.S. Pat. Nos. 4,705,300; 4,705,356; 4,721,271;
5,084,351; 5,214,530; 5,281,480; 5,383,995; 5,569,535, 5,571,624
and in the thereto related documents. When at least a part of the
optically variable pigments consists of thin film interference
pigments, it is preferred that the thin film interference pigments
comprise a Fabry-Perot reflector/dielectric/absorber multilayer
structure and more preferably a Fabry-Perot
absorber/dielectric/reflector/dielectric/absorber multilayer
structure, wherein the absorber layers are partially transmitting
and partially reflecting, the dielectric layers are transmitting
and the reflective layer is reflecting the incoming light.
Preferably, the reflector layer is selected from the group
consisting of metals, metal alloys and combinations thereof,
preferably selected from the group consisting of reflective metals,
reflective metal alloys and combinations thereof and more
preferably selected from the group consisting of aluminum (Al),
chromium (Cr), nickel (Ni), and mixtures thereof and still more
preferably aluminum (Al). Preferably, the dielectric layers are
independently selected from the group consisting of magnesium
fluoride (MgF.sub.2), silicium dioxide (SiO.sub.2) and mixtures
thereof and more preferably magnesium fluoride (MgF.sub.2).
Preferably, the absorber layers are independently selected from the
group consisting of chromium (Cr), nickel (Ni), metallic alloys and
mixtures thereof and more preferably chromium (Cr). When at least a
part of the optically variable pigments consists of thin film
interference pigments, it is particularly preferred that the thin
film interference pigments comprise a Fabry-Perot
absorber/dielectric/reflector/dielectric/absorber multilayer
structure consisting of a Cr/MgF.sub.2/Al/MgF.sub.2/Cr multilayer
structure.
Thin film interference pigments described herein are typically
manufactured by vacuum deposition of the different required layers
onto a web. After deposition of the desired number of layers, the
stack of layers is removed from the web, either by dissolving a
release layer in a suitable solvent, or by stripping the material
from the web. The so-obtained material is then broken down to
flakes which have to be further processed by grinding, milling or
any suitable method. The resulting product consists of flat flakes
with broken edges, irregular shapes and different aspect
ratios.
Suitable interference coated pigments include without limitation
structures consisting of a substrate selected from the group
consisting of metallic cores such as titanium, silver, aluminum,
copper, chromium, iron, germanium, molybdenum, tantalum or nickel
coated with one or more layers made of metal oxides as well as
structure consisting of a core made of synthetic or natural micas,
other layered silicates (e.g. talc, kaolin and sericite), glasses
(e.g. borosilicates), silicium dioxides (SiO.sub.2), aluminum
oxides (Al.sub.2O.sub.3), aluminum oxides/hydroxides (boehmite),
titanium oxides (TiO.sub.2), graphites and mixtures thereof coated
with one or more layers made of metal oxides (e.g. titanium oxide,
zirconium oxide, tin oxide, chromium oxide, nickel oxide, copper
oxide, iron oxide and iron oxide/hydroxide). The structures
described hereabove have been described for example in Chem. Rev.
99 (1999). G. Pfaff and P. Reynders, pages 1963-1981 and WO
2008/083894 A2. Typical examples of these interference coated
pigments include without limitation silicium oxide cores coated
with one or more layers made of titanium oxide, tin oxide and/or
iron oxide; natural or synthetic mica cores coated with one or more
layers made of titanium oxide, silicium oxide and/or iron oxide, in
particular mica cores coated with alternate layers made of silicium
oxide and titanium oxide; borosilicate cores coated with one or
more layers made of titanium oxide, silicium oxide and/or tin
oxide; and titanium oxide cores coated with one or more layers made
of iron oxide, iron oxide/hydroxide, chromium oxide, copper oxide,
cerium oxide, aluminum oxide, silicium oxide, bismuth vanadate,
nickel titanate, cobalt titanate and/or antimony-doped,
fluorine-doped or indium-doped tin oxide; aluminum oxide cores
coated with one or more layers made of titanium oxide and/or iron
oxide.
Liquid crystals in the cholesteric phase exhibit a molecular order
in the form of a helical superstructure perpendicular to the
longitudinal axes of its molecules. The helical superstructure is
at the origin of a periodic refractive index modulation throughout
the liquid crystal material, which in turn results in a selective
transmission/reflection of determined wavelengths of light
(interference filter effect). Cholesteric liquid crystal polymers
can be obtained by subjecting one or more crosslinkable substances
(nematic compounds) with a chiral phase to alignment and
orientation. The particular situation of the helical molecular
arrangement leads to cholesteric liquid crystal materials
exhibiting the property of reflecting a circularly polarized light
component within a determined wavelength range. The pitch can be
tuned in particular by varying selectable factors including the
temperature and solvents concentration, by changing the nature of
the chiral component(s) and the ratio of nematic and chiral
compounds. Crosslinking under the influence of UV radiation freezes
the pitch in a predetermined state by fixing the desired helical
form so that the color of the resulting cholesteric liquid crystal
materials is no longer depending on external factors such as the
temperature. Cholesteric liquid crystal materials may then be
shaped to cholesteric liquid crystal pigments by subsequently
comminuting the polymer to the desired particle size. Examples of
films and pigments made from cholesteric liquid crystal materials
and their preparation are disclosed in U.S. Pat. Nos. 5,211,877;
5,362,315 and 6,423,246 and in EP 1 213 338 A1; EP 1 046 692 A1 and
EP 0 601 483 A1, the respective disclosure of which is incorporated
by reference herein.
The magnetic oxidative drying inks described herein may further
comprise one or more fillers and/or extenders preferably selected
from the group consisting of carbon fibers, talcs, micas (e.g.
muscovites), wollastonites, calcinated clays, china days, kaolins,
carbonates (e.g. calcium carbonate, sodium aluminum carbonate),
silicates (e.g. magnesium silicate, aluminum silicate), sulfates
(e.g. magnesium sulfate, barium sulfate), titanates (e.g. potassium
titanate), alumina hydrates, silica, fumed silica,
montmorillonites, graphites, anatases, rutiles, bentonites,
vermiculites, zinc whites, zinc sulphides, wood flours, quartz
flours, natural fibers, synthetic fibers and combinations thereof.
When present, the one or more fillers or extenders are preferably
present in an amount from about 0.1 to about 40 wt-%, the weight
percents being based on the total weight of the magnetic oxidative
drying ink.
The magnetic oxidative drying inks described herein may further
comprise one or more waxes preferably selected from the group
consisting of synthetic waxes, petroleum waxes and natural waxes.
Preferably the one or more waxes are selected from the group
consisting of microcrystalline waxes, paraffin waxes, polyethylene
waxes, fluorocarbon waxes, polytetrafluoroethylene waxes,
Fischer-Tropsch waxes, silicone fluids, beeswaxes, candelilla
waxes, montan waxes, carnauba waxes and mixtures thereof. When
present, the one or more waxes are preferably present in an amount
from about 0.1 to about 15 wt-%, the weight percents being based on
the total weight of the oxidative drying ink.
The magnetic oxidative drying inks described herein may further
comprise one or more forensic markers and/or one or more
taggants.
The magnetic oxidative drying inks described herein may further
comprise one or more additives including without limitation
compounds and materials which are used for adjusting physical,
rheological and chemical parameters of the composition such as the
viscosity (e.g. solvents, diluents and surfactants), the
consistency (e.g. anti-settling agents, filers and plasticizers),
the foaming properties (e.g. antifoaming agents), UV stability
(photostabilizers) and adhesion properties, etc. Additives
described herein may be present in the magnetic oxidative drying
inks disclosed herein in amounts and in forms known in the art,
including in the form of so-called nano-materials where at least
one of the dimensions of the particles is in the range of 1 to 1000
nm.
The present invention further provides methods for producing the
magnetic oxidative drying inks described herein and magnetic
oxidative drying inks obtained therefrom. The method comprises a
step of dispersing, mixing and/or milling the at least one
oxidative drying varnish described herein, the core-shell pigment
particles, the one or more stabilizers and the one or more
additives when present thus forming pasty compositions.
The magnetic oxidative drying inks described herein are
particularly suitable to be applied by an intaglio printing
processes onto a substrate, in particular the magnetic oxidative
drying inks described herein are particularly suitable to be
applied by an intaglio printing processes onto a substrate so as to
produce a security feature.
Suitable substrates for the present invention include without
limitation papers or other fibrous materials such as cellulose,
paper-containing materials, plastic or polymer substrates,
composite materials, metals or metalized materials, glasses,
ceramics and combinations thereof. Typical examples of plastic or
polymer substrates are substrates made of polypropylene (PP),
polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC) and
polyethylene terephthalate (PET). Typical examples of composite
materials include without limitation multilayer structures or
laminates of paper and at least one plastic or polymer material
such as those described hereabove as well as plastic and/or polymer
fibers incorporated in a paper-like or fibrous material such as
those described hereabove. With the aim of further increasing the
security level and the resistance against counterfeiting and
illegal reproduction of security documents, the substrate may
contain watermarks, security threads, fibers, planchettes,
luminescent compounds, windows, foils, decals, coatings and
combinations thereof.
Also described herein are security features made of the magnetic
oxidative drying ink described herein and security documents
comprising one or more of said security features. Also described
herein are uses of the security features described herein for the
protection of a security document against fraud or illegal
reproduction.
Also described herein are methods for producing a security feature
and security features obtained thereof. The method described herein
comprises a step a) of applying by an intaglio printing process the
magnetic oxidative drying ink described herein onto a substrate
such as those described herein. The method preferably further
comprises a step b) of drying the magnetic oxidative drying ink
described herein in the presence of air so as to form a layer or
coating on the substrate said step of drying being performed after
the step a). The step b) of drying the magnetic oxidative drying
ink described may be performed under hot air, with an infrared
source or any combination of hot air and an infrared source so as
to decrease the drying time of said inks.
Intaglio printing refers to a printing method used in particular in
the field of printing security documents. In an industrial intaglio
printing process, a rotating steel cylinder carrying a plate
engraved with a pattern or image to be printed is supplied with ink
by one or by a plurality of selective inking cylinder(s) (or
chablon cylinders), each selective inking cylinder being inked in
at least one corresponding color to features. Subsequently to the
inking step, the intaglio printing process involves a step of
wiping off any ink excess present on the surface of the intaglio
printing device, said step being carried out using a paper or a
tissue ("calico") or a polymeric roll ("wiping cylinder").
Subsequently, the plate is brought into contact with a substrate
such as those described herein, in sheet form or web form, and the
ink is transferred under pressure from the engravings of the
intaglio printing device onto the substrate to be printed forming a
thick security feature on the substrate.
The step of applying by an intaglio printing process the magnetic
oxidative drying ink described herein onto a substrate such as
those described herein is typically performed with an intaglio
plate having zones of different engraving depth such as to result
in a security feature having printed zones of different levels of
magnetic signal.
Also described herein are security features made of the magnetic
oxidative drying ink described herein. Also described herein are
uses of the security features described herein for the protection
of a security document against fraud or illegal reproduction.
According to one embodiment, the magnetic oxidative drying ink
described herein may be used to produce a security feature in the
form of a magnetic code for a security thread or stripe, wherein
said magnetic code comprises non-adjacent magnetic areas made of
the magnetic oxidative drying ink described herein and areas free
from said ink, wherein both areas are arranged along a
predetermined direction which extends along the longwise direction
of the security thread or stripe. Magnetic codes may be used as
security elements to be incorporated into or onto security
documents to be protected against counterfeiting or illegal
reproduction and to be authenticated. In an embodiment, the
magnetic areas are arranged as bands extending across the stripe or
thread and spaced in the longwise direction of the security thread
or stripe, with the spacing forming bands free from magnetic
oxidative drying ink. The magnetic areas of the magnetic code serve
to store information for automatic reading, decoding or recognition
by a device that detects magnetic variations on the security thread
or stripe.
Also described herein are security documents comprising one or more
security features made of the magnetic oxidative drying ink
described herein such as those described herein.
The term "security document" refers to a document having a value
such as to render it potentially liable to attempts at
counterfeiting or illegal reproduction and which is usually
protected against counterfeit or fraud by one or more security
features. Examples of security documents include without limitation
value documents and value commercial goods. Typical example of
value documents include without limitation banknotes, deeds,
tickets, checks, vouchers, fiscal stamps and tax labels, agreements
and the like, identity documents such as passports, identity cards,
visas, bank cards, credit cards, transactions cards, access
documents, security badges, entrance tickets, transportation
tickets or titles, and the like.
The term "value commercial good" refers to packaging material, in
particular for pharmaceutical, cosmetics, electronics or food
industry that may comprise one or more security features in order
to warrant that the content of the packaging is genuine, like for
instance genuine drugs. Example of these packaging material include
without limitation labels such as authentication brand labels, tax
banderoles, tamper evidence labels and seals.
The security document described herein may further comprise one or
more additional layers or coatings either below or on top of the
security feature made of the magnetic oxidative drying ink
described herein. Should the adhesion between the substrate and the
security feature described herein be insufficient, for example, due
to the substrate material, a surface unevenness or a surface
inhomogeneity, an additional layer, coating or a primer between the
substrate and the security feature might be applied as known for
those skilled in the art.
With the aim of increasing the durability through resistance
against soiling or chemicals and the cleanliness and thus the
circulation lifetime of security documents, one or more protective
layers may be applied on top of the one or more security features
described herein. When present, the one or more protective layers
are typically made of protective varnishes which may be transparent
or slightly colored or tinted and may be more or less glossy.
Protective varnishes may be radiation curable compositions, thermal
drying compositions or any combination thereof. Preferably, the one
or more protective layers are made of radiation curable, more
preferably UV-Vis curable compositions.
EXAMPLES
The present invention is now described in more details with
reference to non-limiting examples. The Examples below provide
greater details for the use of the one or more benzotriazole
compounds of formula (I) described herein as stabilizers for
magnetic oxidative drying inks for intaglio printing (Examples
E1-E3) in comparison with inks comprising different stabilizers
(C1-C4) or lacking a stabilizer (C0a, C0b and C0c).
The amount of the stabilizers, the core-shell pigment particles,
the colored pigments, the driers and filer was kept constant for
all the experimental data.
Intaglio Magnetic Oxidatively Drying Inks (Tables 1a, 1b and
1c)
The intaglio magnetic oxidatively drying inks (E1a, E1b, E1c, E2,
E3, C0a, C0b, C0c, C1, C2 and C3) comprised core-shell pigment
particles, wherein said core-shell pigment particles were prepared
by a two-step process:
1) TiO2 Coating
TiO.sub.2-coated iron was prepared by dispersing 80 g of iron
particles (synthesized from carbonyl iron, d.sub.50 1-10 .mu.m) in
a 2 L solution of anhydrous ethanol comprising 1.2 mL 0.4 M
Lutensol.RTM. ON 50 (BASF). After about 15 minutes of vigorous
stirring, 2.4 mL of titanium isopropoxide (TTIP, Sigma Aldrich)
were added. The reaction was stirred under nitrogen at room
temperature for about two hours and was stirred at room temperature
one night in air.
2) Silver Coating
70 g of the TiO.sub.2-coated iron particles obtained during the
first step were dispersed in 280 mL of distilled water. 1000 mL of
a silver nitrate solution (280 mL of ammonium hydroxide 28 wt-% and
720 mL of silver nitrate (8.7 wt-%. Fisher)) were added dropwise at
70.degree. C. under vigorous stirring. After an additional hour of
stirring at 70.degree. C., 280 mL of a D-glucose solution (28 wt-%,
Acros) was added. The so-obtained yellow precipitate was allowed to
cool to room temperature under stirring, filtered, washed with
distilled water and dried at 80.degree. C. for about 16 hours so as
to obtain the silver coated iron particles having a spherical shape
and having a d.sub.50 value of 1-12 .mu.m.
The intaglio magnetic oxidatively drying inks (E1a, E1b, E1c, E2,
E3, C0a, C0b, C0c, C1, C2 and C3) were prepared by thoroughly
mixing the compounds listed in Table 1a, 1b, and 1c, respectively,
by hand with a spatula until they were visually homogeneous. The
resulting pasty inks were independently grinded on a three-roll
mill (Buhler 200 SDV) in two passes (first pass at 6 bars and
second pass at 12 bars).
The viscosity of the so-obtained intaglio magnetic oxidatively
drying inks was measured on a Haake Roto Visco 1 rotational
rheometer (40.degree. C. and 1000 s.sup.-1, C20-0.5.degree., plate
cone of 20 mm, truncated at 25 .mu.m). Viscosity values are
provided in Table 1a, 1 and 1c.
Preparation of Drawdown Samples
With the aim of simulating an intaglio printed layer, a drop of
about 0.2 g of each intaglio magnetic oxidatively drying ink
described in Tables 1a, 1b and 1c was deposited on a 14.7
cm.times.10.5 cm piece of standard offset paper (120 .mu.m thick,
supplier: Jeco Print Sarl). Each intaglio magnetic oxidatively
drying ink described in Tables 1a, 1b and 1c was pulled down using
a wide blade draw-down knife with a light hand pressure to form an
ink layer of about 8 cm length, 2 cm width and 40 to 60 .mu.m
thickness.
Natural Ageing
The drawdown samples were allowed to dry in the dark for seven
days, then the L*a*b* value (CIELAB 1976) and the NIR reflectance
were measured for the ink layer on the piece of standard offset
paper as described hereabove. The drawdown samples were
subsequently stored in the dark for ten weeks under standard
conditions (22.degree. C., 30% rH), in a normal atmosphere.
Measurements of the L*a*b values (CIELAB 1976) and NIR reflectances
were carried out so as to obtain said data for each drawdown sample
after ageing. The "after ageing" data were compared to the "before
ageing" data, and the change due to natural ageing was expressed as
.DELTA.E* (CIELAB 1976) and a NIR reflectance difference
.DELTA.R.
Accelerated Ageing
The drawdown samples were allowed to dry in the dark for seven
days, then the L*a*b value (CIELAB 1976) and the NIR reflectance
were measured. The drawdown samples were then stored in the dark
for seven days in a desiccator over a saturated sodium sulfide
solution (28.7 wt-% Na.sub.2S, Fluka 71975, Sigma Aldrich) at room
temperature (22.degree. C., 50-60% RH). Measurements of the L*a*b*
values and NIR reflectances were carried out so as to obtain said
data for each drawdown sample after accelerated ageing. The "after
ageing" data were compared to the "before ageing" data, end the
change due to accelerated ageing was expressed as .DELTA.E* (CIELAB
1976) and a NIR reflectance difference .DELTA.R.
Preparation of Intaglio Printed Samples
The intaglio magnetic oxidatively drying inks described in Tables
1a, 1b and 1c were independently applied by a printing process
using an Ormag intaglio proof-press. The intaglio magnetic
oxidatively drying inks were independently applied on the intaglio
plate with a polymer hand-roller and any ink excess was wiped off
manually with paper. Printing was carried out with a printing plate
(temperature of 65.degree. C.) on a standard cotton paper substrate
used for banknote applications (Louisenthal). The intaglio plate
used to print the examples was composed of a set of engravings of
various depths (from about 20 .mu.m to about 100 .mu.m) and widths
(from about 60 .mu.m to about 500 .mu.m), engraved with a
"U"-shape, such as to simulate an intaglio printed image on a
banknote.
For each example, an image sample was printed according the method
described hereabove. The samples were kept 24 hours at 22.degree.
C. and 50% rH under 3 kg pressure to simulate a pie of printed
substrates. A blank piece of the same substrate was subsequently
applied over the image sample and the so-formed assembly was
submitted to a counterpressure of 3.4 bars at 80.degree. C. with
the same ORMAG Intaglio Proof Press. The image sample and the blank
piece were separated and the blank piece was checked for ink
transfer in order to assess the drying performance as described
hereafter.
Results of Intaglio Magnetic Oxidatively Drying Inks (Tables 1a, 1
b and 1c)
A) Stability of Visible Optical Properties: .DELTA.E* Values
(CIELAB 1976)
The visible color difference between drawdown samples of the
intaglio magnetic oxidatively drying inks described in Tables 1a,
1b and 1c before and after ageing according to the methods
described herein is expressed as .DELTA.E* CIELAB (1976). The
CIELAB (1976) values were measured with a spectrophotometer DC 45
from Datacolor (measurement geometry: 45/0.degree.; spectral
analyzer: proprietary dual channel holographic grating.
256-photodiode linear arrays used for both reference and sample
channels; light source: total bandwidth LED illumination).
.DELTA.E* values for each drawdown sample before and after ageing
were calculated according to the following equation:
.DELTA.E*=[(.DELTA.L*).sup.2+(.DELTA.a*).sup.2+(.DELTA.b*).sup.2].sup.1/2-
=[(L*(sample after ageing)-L*(sample before
ageing)).sup.2+(a*(sample after ageing)-a*(sample before
ageing)).sup.2+(b*(sample after ageing)-b*(Sample before
ageing)).sup.2].sup.1/2, wherein
.DELTA.L* is the lightness difference
.DELTA.a* is the red/green difference
.DELTA.b* is the blue/yellow difference
For each sample, three individual spots were measured before and
after ageing.
The .DELTA.E* values indicated in Table 1a, 1b and 1c correspond to
an average value of three measurements.
Larger .DELTA.E* values indicate stronger deviation between the
color of the sample before ageing and after ageing.
B) Stability of NIR Reflectance: .DELTA.R at 850 nm
NIR reflectances were measured on a piece of standard offset paper
as described hereabove using the DC 45 from Datacolor at 850 nm.
The difference in reflectance between the drawdown samples of the
intaglio magnetic oxidatively drying inks described in Tables 1a,
1b and 1c before ageing and after ageing was determined as
.DELTA.R. The 100% reflectance was measured using the internal
standard of the device.
For each sample, three individual spots were measured before and
after ageing. The .DELTA.R values indicated in Table 1a, 1b and 1c
correspond to an average value of three measurements.
C) Drying Performance (Relative to C0a/C0b/C0c)
The drying performance of the intaglio magnetic oxidatively drying
inks described in Tables 1a, 1b and 1c was carried out on the
samples printed with an Ormag intaglio proof-press as described
hereabove.
For each example, a scan of the blank piece prepared according to
the method described hereabove was made using an Epson 7680 Pro
color scanner, in RGB mode (8-bit per color channel) at a
resolution of 600 dpi, so as to yield a *.tif uncompressed file.
Each scan was opened in Photoshop CS 6.
The number of pixels transferred from the image sample to the blank
piece was determined using the following method: the magic wand
(settings: point sample, anti-alias off, contiguous off) was set to
32% tolerance, and a location where no ink transfer occurred was
selected (corresponding to almost full white). "Select" and
"inverse" were then applied to yield a selection containing only
the transferred pixels. Finally, the number of transferred pixels
was determined using the histogram.
For each scan, the sequence was repeated three times, randomly
starting at different locations (full white) of the blank piece,
and an average value of transferred pixels was calculated (final
precision: .+-.5%). The average number of transferred pixels for
each of the examples E1, E2, E3, E4, C1, C2, and C3 was compared
with the average number of the transferred pixels of the reference
(C0a, C0b and C0c) and given as a %-difference (A %) in Tables 1a,
1b and 1c. This indicated the drying performance of each intaglio
magnetic oxidatively drying ink of Tables 1a, 1b and 1c by
comparison with the reference (C0a, C0b and C0c). The higher the
%-difference compared to the reference, the worse the ink drying
performance.
D) Drying Performance (Relative to C0c Dry Sample)
The average number of transferred pixels as measured hereabove was
compared to the number of pixels of a fully dried sample (drying
conditions: one week at room temperature). This sample was printed
using the same ink as C0c (Table 1c), using the printing method
described hereabove, and scanned using the method described
hereabove. The average number of transferred pixels for each of the
examples C0a, C0b. C0c, E1, E2, E3, E4, C1, C2, and C3 was compared
with the number of pixels of the fully dried sample using the
following formula:
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times. ##EQU00001##
This indicated the absolute drying performance of each intaglio
magnetic oxidative drying ink of Tables 1a, 1b and 1c. The higher
the %-value compared to the fully dried sample, the better the ink
drying performance. The performance was considered as "excellent"
when the %-value exceeded 95%, it was considered as "good" when the
%-value was comprised between 90% and 95%, and it was considered as
"sufficient" when the %-value was comprised between 85% and 90%.
All values below 85% were considered "insufficient."
TABLE-US-00001 TABLE 1a E1a E2 C0a C1 ingredients wt-% wt-% wt-%
wt-% Ink formulation Phenolic resin (varnish) 14.9 14.9 14.9 14.9
Alkyd resin (binder) 41.8 41.8 41.8 41.8 CaCO.sub.3 (filler) 18.4
18.4 20.4 18.4 Core-shell pigment particles 12 12 12 12 Pigment
Yellow 174 5 5 5 5 Carnauba wax 4.7 4.7 4.7 4.7 Co-octoate (metal
content 12 wt-%) (drier) 0.2 0.2 0.2 0.2 Mn-octoate (metal content
8 wt-%) (drier) 1 1 1 1 Stabilizer (see structure in Table 2) 2
(I1) 2 (I2) 0 2 (I3) results Viscosity [Pas] 4.3 4.2 4.3 3.5
Stability.sup.a of visible optical properties, .DELTA.E* 4 5 16 10
Stability.sup.a of NIR reflectance, .DELTA.R at 850 nm 5 6 10 6
Stability.sup.b of visible optical properties, .DELTA.E* 4 4 44 13
Stability.sup.b of NIR reflectance, .DELTA.R @ 850 nm 0 -8 13 9
Drying performance, transferred pixels 81142 19346 51822 37485
.DELTA.% of reference (C0a) +57% -63% 0% -28% Absolute drying
performance % 85% 94% 90% 93% sufficient good good good
.sup.anormal ageing, .sup.baccelerated ageing
As can be seen in Table 1a, the intaglio magnetic oxidative inks
comprising the one or more benzotriazole compounds of formula (I)
as stabilizers (E1a, E2) exhibited an improved stability of the
visual optical properties (.DELTA.E*) not only after ten weeks of
normal ageing but also after one week of accelerated ageing in a
Na.sub.2S atmosphere, in comparison with the intaglio magnetic
oxidative ink lacking said compounds (C0a). The comparative
intaglio magnetic oxidative ink comprising a stabilizer different
from formula (I) (C1) did not exhibit a strongly improved stability
in comparison with the ink lacking a stabilizer (C0a).
E1a and E2 consist of intaglio magnetic oxidative inks exhibiting
sufficient to good drying performance while having improved optical
properties in the visible and the NIR.
TABLE-US-00002 TABLE 1B E1b E3 C0b C2 ingredients wt-% wt-% wt-%
wt-% Ink formulation Phenolic resin (varnish) 14.9 14.9 14.9 14.9
Alkyd resin (binder) 29.3 29.3 29.3 29.3 High-molecular weight
alkyd resin (binder) 12.5 12.5 12.5 12.5 CaCO.sub.3 (filler) 18.4
18.4 20.4 18.4 Core-shell pigment particles 12 12 12 12 Pigment
Yellow 174 5 5 5 5 Carnauba wax 4.7 4.7 4.7 4.7 Co-octoate (metal
content 12 wt-%) (drier) 0.2 0.2 0.2 0.2 Mn-octoate (metal content
8 wt-%) (drier) 1 1 1 1 Stabilizer (see structure in Table 2) 2
(I1) 2 (I4) 0 2 (I5) results Viscosity [Pas] 9.9 9.3 9.6 8.0
Stability.sup.a of visible optical properties, .DELTA.E* 3 4 14 23
Stability.sup.a of NIR reflectance, .DELTA.R at 850 nm -3 2 13 17
Stability.sup.b of visible optical properties, .DELTA.E* 1 1 30 24
Stability.sup.b of NIR reflectance, .DELTA.R @ 850 nm -2 2 5 6
Drying performance, transferred pixels 31128 16642 19541 138524
.DELTA.% of reference (C0b) +59% -15% 0% +609% Absolute drying
performance % 94% 97% 96% 74% good excellent excellent insufficient
.sup.anormal ageing, .sup.baccelerated ageing
As can be seen in Table 1b, the intaglio magnetic oxidative inks
comprising the more benzotriazole compounds of formula (I) as
stabilizers (E1b, E3) exhibited an improved stability of the visual
optical properties (.DELTA.E*) not only after ten weeks of normal
ageing but also after one week of accelerated ageing in a Na.sub.2S
atmosphere, in comparison with the intaglio magnetic oxidative ink
lacking said compounds (C0b). The comparative intaglio magnetic
oxidative ink comprising a stabilizer different from formula (I)
(C2) did not exhibit any improved stability in comparison with the
ink lacking a stabilizer (C0b).
E1b and E3 consist of intaglio magnetic oxidative inks exhibiting
good to excellent drying performance while having improved optical
properties in the visible and the NIR.
TABLE-US-00003 TABLE 1c E1c C0c C3 C4 ingredients wt-% wt-% wt-%
wt-% Ink formulation Phenolic resin (varnish) 13.1 13.1 13.1 13.1
Alkyd resin (binder) 26.9 26.9 26.9 26.9 High-molecular weight
alkyd resin (binder) 16.7 16.7 16.7 16.7 CaCO.sub.3 (filler) 18.4
20.4 18.4 18.4 Core-shell pigment particles 12 12 12 12 Pigment
Yellow 174 5 5 5 5 Carnauba wax 4.7 4.7 4.7 4.7 Co-octoate (metal
content 12 wt-%) (drier) 0.2 0.2 0.2 0.2 Mn-octoate (metal content
8 wt-%) (drier) 1 1 1 1 Stabilizer (see structure in Table 2) 2
(I1) 0 2 (I6) 2 (I7) results Viscosity [Pas] 10.2 9.6 8.9 10.6
Stability.sup.a of visible optical properties, .DELTA.E* 7 20 16 10
Stability.sup.a of NIR reflectance, .DELTA.R at 850 nm 9 16 20 16
Stability.sup.b of visible optical properties, .DELTA.E* 7 24 12 10
Stability.sup.b of NIR reflectance, .DELTA.R @ 850 nm 8 25 14 17
Drying performance, transferred pixels 53171 53720 64471 143402
.DELTA.% of reference (C0c) -1% 0% +21% +170% Absolute drying
performance % 90% 90% 88% 78% good good sufficient insufficient
.sup.anormal ageing, .sup.baccelerated ageing
As can be seen in Table 1c, the intaglio magnetic oxidative ink
comprising the more benzotriazole compounds of formula (I) as (E1c)
exhibited an improved stability of the visual optical properties
(.DELTA.E*) not only after ten weeks of normal ageing but also
after one week of accelerated ageing in a Na.sub.2S atmosphere, in
comparison with the intaglio magnetic oxidative ink lacking said
compounds (C0c). The comparative intaglio magnetic oxidative inks
comprising a stabilizer different from formula (I) (C3 and C4) did
not exhibit a strongly improved stability in comparison with the
ink lacking a stabilizer (C0c).
E1c consists of an intaglio magnetic oxidative ink exhibiting good
drying performance while having improved optical properties in the
visible and the NIR.
TABLE-US-00004 TABLE 2 Stabi- Commercial lizer Structure CAS name
Supplier I1 ##STR00005## 29385-43-1 Wintrol .RTM. TPF Wincom I2
##STR00006## 1548-67-0 5- (trifluorometh- yl)-1H-1,2,3-
benzotriazole ABCR I3 ##STR00007## 13351-73-0 1-methyl- 1,2,3-
benzotriazole ABCR I4 ##STR00008## 95-14-7 Preventol .RTM. BZT
Lanxess I5 ##STR00009## 2440-22-4 Tinuvin .RTM. P BASF I6
##STR00010## 25-75% 80584-90-3 and 25-75% 80595-74-0 Cobratec .RTM.
122 Raschig I7 ##STR00011## 46% 80584-88-9, 30% 80584-89-0, and 20%
water Cobratec .RTM. 178 Raschig
* * * * *